Electronic computer



July 13, 194s.

Filed Oct. 21, 1943 Figi/1 I9 i dw L. El FLQRY ELEcTRoNIc COMPUTER 3 Sheets-Sheet 1 Q5/MVL 7 /PL C 19 :im II f: l /T F Gttomcg July 13, 1948. l.. EJFLORY v2,445,215

ELECTRONIC COMPUTER Filed Oct. 21, 1945 3 Sheets-Shet 2 OOv O OO

Gttorncg July 13, 1948. L. EL'FLORY ELEcTRomc couru'rrm hunted July is, 194s 2,445,215 ELECTRONIC CCMPUTER Leslie E. Flory, Princeton, N. J.,

alaignor to Radio Corporation of America, a corporation of Deiaare ApplicationOctober 21, 1943, Serial No. 597,131 12 Claims. ((1235-61) ai such pulses.

The present application is a continuation-inpart ci an application Serial No. 467,229, filed November 28. 1942, now abandoned.

The basic circuit utilized in adapting the invention herein to the various circuits to be described is the well known trigger" circuit of the general type described in Theory and Application of Vacuum Tubes by Herbert J. Reich. In one of its simplest forms, this trigger circuit includes two triodes in which the grid of the ilrst triade is coupled ta the anode of the second triade through a network comprising a parallel connected resistor and capacitor, and the grid of the second triade is similarly coupled to the anode of the first triade through a similar coupling network. The cathodes of both triades are grounded, either directly, or through suitable cathode resistors. Gridfandanode potentials are applied to the respective electrodes through separate resistors. If desired, a gaseous discharge tube may be cannected across one of the anode resistors to indicate circuit operation.

In operation, to the grid of the ilrst triade, the anode current of the triade will be reduced and the anode potential will become more positive. Due to the connection through the coupling resistor, the grid potential of the second triade will become more positive, causing an increase in the anode current of the second triade, with a resultant decrease in the second triade anode potential. This decrease in anode potential will, in turn, cause the grid potential af the first triade to become more negative. 'Ihis action will continue, because of the diierenoe in the potential charges on the coupling capacitors. until the anode current of the iirst triade is cut oil. The nrst triade will remain cut oit, and the second triade will remain conducting, until a positive potential is applied tothe grid of the iirst triade or a negative potential is applied to the grid of the second triade. In either latter instance, the tube operating conditions will be reversed and the iirst triade willf r' me conducting and the anode current oithe second triade will be cut oil.

One of the features of the instant invention is the utilization of such trigger circuits in cascade arrangement, whereby a predetermined change in the polarization or activization of one triade ai' the trigger circuit will generate a pulse to it a negative voltage is applied trig'ger or activate a succeeding trigger circuit in the cascade arrangement. As many trigger circuits as desired may be connected in cascade. The instant invention is a modification of that disclosed in the copending U, S. application of George A. Morton and Leslie E. Flory, Serial No. 459,404, tiled September 23, 1942, now Patent No. 2,442,403, granted June 1, 1948, which describes a cascade trigger circuit arrangement for counting voltage pulses to derive a sum in the scale oi 10. It is also an improvement on the invention of another copending U. S. application ai George A. Morton and Leslie E. Flory, Serial No. 464,292, tiled November 2, 1942, now Patent No. 2,409,689, granted October 22, 1946, and entitled Electronic computing devices. The instant invention, however, is adapted to the direct multiplication of two binary numbers which are applied to the apparatus in the form of groups of potentials. In addition, provision is made for deriving directly the binary product of' two or more binary numbers represented by succeeding series of voltage pulses.

In the last mentioned copending application, multiplication is accomplished by deriving the binary sum of a binary multiplicand added to itself a number of items which is equal to the multiplier. In the instant invention, multiplication is accomplished by deriving the binary sum of a binary multiplicand added to the same multiplicand once for each occurrence of a binary i in the multiplier, and in which successively added numbers are stepped over one step for each term in the multiplier,

The binary system of computation is particularly suited to electronic computers since a coinplete binary term of a binary number may be expressed in terms ai either the conducting condition or the cut-off condition of the anode circuit of a conventional vacuum tube. A saving in the number of tubes required for a given number is also possible in a ratio of 3 to 1 over the scale ai' 10 system. A more complete discussion of the binary system of computation may be found in Elementary Number Theory by Uspenskl and Heaslet.

In order to operate a computer utilizing the binary system, it is necessary to adapt the conventional trigger circuit described heretofore to eiiect a reversal in polarization or activization by succeeding applied-pulses of a similar nature. Some of the circuits to be described hereinafter are adapted to this purpose by applying in a symmetrical manner negative operating pulses to the anode circuits of the trigger tubes.

4plied pulses. Another object is animals,

Among the objects o1' the invention are to provide a new and improved means for counting voltage pulses. Another object of the invention is to provide improved means for utilizing conventional trigger circuits in a novel cascade arrangement for deriving the product of quantities represented by the numbers oi' pulses in successive series ot voltage pulses. Still another object is to provide an improved means for connecting conventional trigger circuits in cascadeiarrangement to provide a continuous computer. Ak further object is to provide improved means for clearing the computer after each operation thereof, for conditioning the circuit for counting succeeding apto provide an improved means for deriving the binary product of two or more binary numbers represented by successive groups of potentials applied to a therf mionic tube trigger circuit. Still another object is to provide a new and improved means for deriving the binary product of the binary sums oi succeeding series of voltage pulses wherein the multiplicand and multiplier are applied as binary numbers to separate series oi cascaded trigger circuits.

The invention will be described by reference to the accompanying drawings, of which Fig. 1 is a schematic circuit diagram of the binary shifting circuit, Fig. 2 is a partial block circuit diagram of one embodiment of the invention, Fig. 3 is a partial block circuit diagram of a second embodiment of the invention, Fig. 4 is a block circuit diagram of the complete embodiment partially shown, in Fig. 2, Fig. 5 is a Wiring diagram oi.' a part of the computing system of Fig. 4, and Fig. 6 illustrates the electronic switch through which multiplier and stepping pulses are applied to the computing system oi Fig. 4. Similar reference numerals are applied to similar elements throughout the drawings,

Referring to the drawings, Fig. l. comprises a trigger circuit of the general type described heretofore, which is adapted to the the multiplicand for successive terms of the binary multiplier. The grid gl of a lrst triode l is connected to the anode p2 of a second triode 2 l through a network comprising the parallel connected resistor 5 and capacitor il. The anode pi of the irst triode i is connected to the grid g2 of the second triode 2 through a second network comprising the parallel connected resistor 3 and capacitor 4. The cathodes of the lrst and second triodes i, 2 are grounded through separate resistors. A source of negative biaspotential c is connected to the grldgi of the first tube I through a grid resistor l, and to the grid g2 of the second triode 2 through a second grid resistor il. lThe positive terminal of the bias source c is grounded. Anode potential from a source B is 'applied to the anode pi of the rst' tube i through an anode coupling resistor 9, and to the anode p2 of the second tube 2 through a second anode coupling resistor It. The negative terminal of the anode potential source B is grounded.

A gaseous indicator tube it, which may be a conventional neon tube, is connected across the second anode resistor il to indicate Whenthe anode current exceeds a. predetermined value, characteristic oi the anode current conducting condition of the second tube 2. A choking resistor i4 is con-s nected in series with the positive anode power supply lead to the common terminals of the anode resistors t and ill. Negative input control pulses are applied to the input teminais it between ground and the common terminal of the anode displacement of switch is closed. The positive resistors 9 and I l, through an input coupling capacitor I C. l

In operation, if it is assumed that the rst tube I initially is drawing anode current. the second tube 2 will be biased oil?. A negative pulse applied to the input terminals I5 will appear on the anode p2 of the tube 2 and on the grid gI of the ilrst tube I which will, in turn, reduce the anode current in the ilrst tube I. This, in turn, will make the potential on the anode pI of the first tube I more positive, and degenerate simultaneously any ofthe original negative pulses applied at pl. A positive pulse will be applied to the grid g2 of the tube 2, causing the tube 2 to become conducting. This effect will increase and continue, because of the difference in the potential charges on the capacitors 4 and 6, until the first tube I is cut ofi', and the second tube 2 becomes completely conducting. A subsequent negative pulse applied to the input terminals I5 will cause the stable conditions of the trigger tubes I, 2 to be reversed since the circuit is completely symmetrical.

The indicator tube I3 will be illuminated when the first tube I is conducting, since only under this condition is there an appreciable voltage drop across the anode coupling resistor 9. If it fs assumed that the conducting condition of the first tube pI represents one, and the conducting con dition of the second tube 2 represents zero, the result is a. binary set-up system in which zero is indicated on the indicator tube I3 when the tube is extinguished, and one is indicated when the tube is illuminated. The second pulse applied to the input terminals I5 will cut ofi* the second trigger tube 2 and cause the rst tube I again to become conducting. VIn order to indicate that two pulses have occurred instead of none, it is essential that a carryover system be employed which will provide a second indication representative of the second term of the binary total. This feature will be described hereinafter in connection with the product computer circuit of Fig. 4l. if a carryover circuit is desired for the multiplicand set-up systemfit may be of the type described in the second copending application mentioned heretofore. However, to simplify the present description, it is assumed that a binary multiplicand is directly set up on the multiplicand set-up system, through the separate input terminals i5, i5', i5".

It will be seen that the circuit of Fig. l employs three identical trigger circuits connected in a novel cascade arrangement whereby three terms of a binary number may be set up as a binary multiplicand. As illustrated, the circuit comprises three trigger circuits of the general type described heretofore, but it should be understood second trigger tubes i and 2, comprising the trig ger circuit I and the rst indicator tube i3 correspond to the :first term of the binary number. The subsequent trigger circuits' II and Ill correspond respectively to the second and third terms of the binary multiplicand. The grids ofthe tubes i and il are connected respectively through suitable choking resistors il and it? to a ixed contact of a reset switch S-i. The movable contact of the reset switch S-i is connected to the negative terminal of a potential source D to provide cutfo grid bias for the tubes i and il when the terminal of the biss potential source Dis grounded.

To accomplish the multiplicand shifting, the

shift pulses are applied to the grid glrof the iirsttube of each of the trigger circuits I. 1I and III through capacitors 2li, 2l' and 23", respectively, which have a capacity of the order of 20 mmf. A coupling capacitor 23, which has a capacity of the order of 100 mmf., connects the anode pI of the first tube I of the trigger circuit I to the grid of the first tube I I of the second trigger circuit II. A similar capacitor 23' couples the anode of tube Iltothegridoftube2l.

Assuming the reset switch sl to be open and the tube 2 to be conducting, the application of a negative pulse at the terminals I causes current to be transferred from the tube 2 to the tube I, thereby illuminating the indicator I3. A second negative impulse similarly applied transfers current from the tube I to the tube 2. Negative pulses applied to terminals I5 and I5" similarly affect the units II and III.

The multiplicand shifting operation of the circuit, in response to shift pulses derived from each u term of the binary multiplier, may be described as follows: Ass'ume that the grids of the trigger tubes I and II are at positive potential and that the grid of the trigger tube 2| is at negative potential. This will mean that the condition of the circuit may representthe binary number 011. A negative shift pulse is applied to the grids of all three of the trigger tubes I, II and 2| through the respective capacitors 2II, 20 and 2li". The

anode current of the tube I will be cut off, thereu after indicating binary 0, and a positive pulse will be applied to the grid of tube through the capacitor 23. The negative shift pulse will also start to make the tube non-conducting, thereby causing a positive pulse to be applied from its anode through the relatively large capacitor 23' to the grid of the tube 2| and making this tube conductive. The tube II does not reach a stable conducting condition, however, due to fi positive impulse which is applied to it from the anode of the tube I when this tube becomes nonconducting. Therefore, the circuit condition will now represent the binary number 110, or, in other words, the number 011 has been moved one digital position to the left. This method is applied, as described hereinafter. to shift the multiplicand, or the product. y

One method of multiplyingr two binary nurnbers is schematically illustrated in Fig. 2. A binary multiplicand is set up, in any known man; ner, on the trigger circuits I, II, III, IV of the multiplicand set-up system, which comprises a plurality of trigger circuits connected asdescribed in Fig. l. A multiplier pulse is derived from a multiplier set-up system for each binary 1 term therein. A shift pulse is also derived from the multiplier set-up system for each term in the multiplier.

The multiplier pulses are transmitted to a product totalizer including the trigger circuits XI, XII, XIII, XIV, XV, XVI and XVII for each term of the multiplicand which happens to be binary 1. The means for accomplishing this is described in detail in the second copending application referred to heretofore and is includedy hereinafter under the description of Fig. 4.

As each term of the multiplier, from the lowest to the highest, either delivers a multiplier pulse or fails-to do so, depending upon the binary value of the term, a second or shiftpulse is derived which is applied to the circuit described in Fig. 1 to shift the multiplicand one place for each term in themultiplier. It will therefore be seen that the product totalizer will provide the sum of the multiplicand transferred a numberv of timesand occupying places which correspond to the number and place occurrence of binary 1 terms in the multiplier.

The operation of Fig. 3 is similar to Fig. 2 with the exception that the shift pulses are applied to the product totalizer. In this arrangement. trigger circuits XI, XII, MII, XIV. XV, XVI and XVII, which are interconnected as described in Fig. 1, are used in the product totalizer instead of in the multiplicand set-up system, as in Fig. 2. Carryover amplifiers 50, 5I, 52, 53, 5|, 55, and 53, described hereinafter, in Fig. 4, are interconnected between successive trigger circuits of the totalizer.

The multiplier shift pulses are applied to the product totalizer through the capacitors 2l, 2l', 20" to shift the intermediate product back one place between each successive multiplier pulse, or absence of a pulse, corresponding to successively higher terms in the multiplier.

In order to prevent'a short circuit of product carryover pulses due to by-passing the carryover amplifiers 50, 5I, 52, 53, 54, 55, 5l by the capacitors 23, 23', 23", etc. of the shifting circuit, amplifiers 35, 3l, 33, etc. are inserted in series with the capacitors 23, 23', 23", etc. respectively. These amplifiers are normally biased below cut-off, but are connected to the source of shifting pulses, which pulses reduce the amplifier bias just to cut-off during the duration of the shift pulse. Since the multiplier pulses are interspersed between the shifting pulses, the amplifiers present a high impedance shunt circuit to the carryover pulses. A similar arrangement could be used in the multiplicand trigger circuits if these circuits are also to be used as a set-up system for establishing the binary multiplicand from a source of pulses.

Fig. 4 comprises a block diagram of an electronic multiplying system wherein a multiplicand is set up as a binary number on 'a series of cascaded trigger circuits of the general type described heretofore. The binary multiplicand is then transferred to a second binary totalizer upon which the binary product is derived. The circuits to be described hereinafter accomplish both the direct transfer of the multiplicand to the product totalizer 'and the carryover operation required as each element of the product totalizer changes from one to zero in the binary system. Each of the trigger circuits I, II, III, IV, V, VI and VII of the multiplicand set up system is connected, through leads 90, 9|, 32, etc., to a corresponding transfer amplifier 3l, 3|, 32, 33, 34, 35 and 35, respectively, in such a manner that when the set-up system trigger circuit is in the binary zero condition, the amplifier tube is biased well beyond cut-oil.' and when the set-up system is in the binary 1 condition, the corresponding amplitier is biased :lust to the anode current cut-off condition.

Pulses are applied as described heretofore, to the input terminals I5, I5', I5", I5'." of the multiplicand binary set-up system to establish the multiplicand as a binary quantity on, for example'y the trigger circuits I, Il, III and IV. Pulses which correspond to the presence of binary 1 terms of the binary multiplier are successively applied simultaneously to all of the respective grid circuits of the transfer amplifiers 3l, 3|, 32, 33, 34, 35 and 36. Means for deriving the pulses 43 from a binary multiplier will be described hereinafter. The multiplier pulses will be transmitted by only the transfer amplifiers which are biased to cut-of! and which are connected to the corredue to pulses s sponding multiplicand trigger circuits in the binary 1 condition. The'pulses transmitted by the respective transfer amplifiers are next applied to separate differentiating circuits 40, 4|. 42, 43, 44, 43 and 4I, respectively, from which are derived a positive pulse 41 and a negative pulse 43, separated by the width of the multiplier pulses 43. These pulses are next applied directly to the product binary totalizer comprising the trigger circuits XI, XII, XIII, XIV, XV, XVI, XVII and XVIII, respectively. Th'epositive pulse 41 is utilized to accomplish the carryover operation between successive product totalizer trigger circuits whenever it is applied to one of the trigger circuits which is in thebinary l condition. The negative pulse 40 is utilized to trigger the corresponding product binary trigger circuit to the next binary number. Both' negative and positive pulses 40l and 41, respectively, are applied to the input of a second group of' transfer amplifiers 30, 5|, 52, 53, 34, v53 and 30, respectively, which are connected to the corresponding product trigger circuits. Y The second fiers are connected by the leads m so that they are inoperative when the corresponding product trigger circuit is in the binary zero condition, and are just cut oil when the corresponding trigger circuit is in the binary 1 condition. The outputs of the second transfer amplifiers are connected by the leads n to trigger the next succeeding trigger circuits oi' the product counter. It will therefore be seen that if the first product trigger circuit XI is in the binary 1 condition, the transfer amplifier 50 will be just `cut oil'. Th'e positive pulses 41, applied to the input of Ithe transfer amplifier, will therefore provide a negative pulse in the lead n to the second product trigger circuit XlI. The negative pulse 40. which immediately follows the positive pulse 41, will then trigger the first product trigger circuit XI to the binary zero condition by means of the directly transmitted pulse over the connection k.

A condition may arise, for example, where successive carryover pulses are applied to successive circuits in which no positive or negative pulses 41,48 exist due to th'e fact that the corresponding term in the multiplicand is binary zero, and the corresponding product trigger circuit is initially also in the binary zero condition. This condition is now considered in connection with Fig. 5, which is identical with Fig. 3 of the aforesaid copending application Serial No. 464,292 and has its corresponding parts indicated by the same reference numerals as those of the previous figxures. As pointed out in Serial No. 464,292, the

function of the diodes |93 and |34 is to transmit impulses to the totalizer umts XI and XII and to preventI reaction on preceding trigger circuits in subsequent binary term trigger circuits. Other functions performed by the circuitl of Fig. 5 will be understood from the previous explanation and from the following statement of its operation. i

It is assumed as a starting condition that the unit I is in a binary one condition and the units II, XI and XII are in a binary zero condition. Under these conditions, the transfer amplier 30 is biased to cut off and the amplifiers 3|, 50 and 5I are biased beyond cut off.

The first multiplier pulse (applied through lead |95) operates through |93 to change the unit XI to a binary one condition and to bias the amplifier 50 to cut off.

The second multiplier pulse operates through 50 and |94 to change the unit 'XII to a binary one condition and to bias the amplifier 0| to cut ci! now being 11 or 3 in the decimal system.

transfer ampli- The fourth multiplier pulse operates through the transformer 00 and the ampliiler Il to change the unit XIII toa binary one condition, through |94 to change the unit XII'to a binary zero ccnditlon and through' |03 to change the unit XI to a binary zero condition, the count now being or 4 in the decimal system.

Further steps in the operation of the computing system will be understood without detailed explanation.

The number of trigger circuits utilized in the multiplicand set up system will be equal to the sum of the numbers of binary terms in the multiplicand and the multiplier. The number of trigger circuits required in the product totalizer will be one more than the sum ofthe number of binary terms in the multiplicand and multiplier, respectively. Indicator lamps may be connected in the anode circuits of theindividual trigger circuits of the product totalizer in the same manner as described heretofore in Figure 1 for the individual trigger circuits of the multiplicand setup system. Likewise, the anode circuits of the product totalizer may be connected to apply the Y binary `product directly to other utilization circuits. i.

The multiplier. which may .be in the form of potentials representative of a binary number, is applied directly to a multiplier set-up system comprising a plurality of trigger circuits 10, 1|, 12, 13, of the type described in Fig. 1, with the exception that the capacitors 20. 20', 20" and 23, 23', 23" are omitted. `Potentials indicative of either the binary 0 or the binary 1 conditions of -the individual multiplier trigger circuits 10, 1|,

12, 13 are applied to stationary contacts of an electronic switch or distributor 14. The switch 14 and its various connections is shown by Fig. 6. It includes a plurality of fixed contacts 96 to 39 which have their respective potentials controlled by the multiplier units 10 to 13 and which receive a beam of electrons from a cathode |04, the position of this beam being determined by the potentials applied y to the deiiecting electrodes IUS-|06 from a scanning voltage source |01. Multiplier pulses thusl derived are applied to the transfer amplifiers 30 to 36 of Fig. 4.

The switch 14 also includes fixed contacts |00 to |03 which are subjected to the potential of a source |08 yand which cooperate with a cathode |09 and'deilect-ors |0 and l (connected to the source |01) to generate stepping pulses which are applied yto the units Ito VII of Fig. 4 for stepping the multlpllcand one step along the mul-tiplicand set-up system after the application of each multiplier pulse to the transfer amplifiers.v The scanning may be accomplished by applying scanning potentials of any desired frequency to beam deflecting elemen-ts. The switch should preferably be so arranged that one scanning beam slightly leads Vthe other scanning beam, in order that two separate distinctive pulses may be derived from each multiplier trigger circuit, followed by additional pairs of pulses derived from each of the succeeding multiplier trigger circuits. A negative multiplying pulse 49, which is preferably of square wave form, is thereby derived from one beam of autant the electronic switch 14 each time a contact connected to a multiplier trigger circuit in the binary 1 condition is scanned.

In addition, stepping pulses Il. also .preferably of square wave form, are derived from the other beam of the electronic switch each time this beam passes over the individual contacts of the second group. Thus. as the switch covers the contacts connected to the individual multiplier trigger circuits, a multiplying pulse is derived, providing the multiplier term is binary 1, for keying .the transfer ampliilers to 36 which happen to be unblocked by the respective multiplicand trigger circuits. Immediately thereafter, and irrespective of the condition of the particular multiplier trigger circuit, a second pulse Il is derived from the switch, and applied to all of the multiplicand trigger circuits I, II, III, IV, V, VI, VII to step the multiplicand along the multiplicand counter. After the beams of the switch 1I have scanned all of the switch contacts, no more pulses I9, 68 are derived until a new multiplier is set up on the multiplier counter.

Any other well known electronic or mechanical sequential switching means may be employed, providing two separate and distinctive pulses may be obtained for each term of the multiplier in proper sequence to provide both transfer and shifting of the multiplicand as described heretofore.

All trigger circuits may be cleared after each multiplying oper-ation is completed by applying a high negative bias simultaneously to all binary 1 tubes in the manner which is described in Fig. 1.-

Thus the invention described comprises an electronic multiplying device in which the multiplicand is applied to a cascaded binary counter and transferred to a second or product binary to- .talizer, a number of times corresponding to the binary 1 terms in the multiplier, while simultaneously the multiplicand is shifted a number of times equal to the number of terms in the multiplier. Provision may be made in both the setup and totalizing systems to accomplish binary carry-over operations where required, and to segregate the carryover operation from the direct application of the multiplicand to the product totalizer.

I claim as my invention:

1. 'I'he combination of means for producing potentials representative of a multiplicand,-a totalizer for establishing potentials representative of a product, means for applying pulses representative of a multiplier, amplifier means biased to conditions dependent on said multiplicand-representative potentials Iand responsive to said pulses for transferring said multiplicand to said totalizer .once for each occurrence of a predetermined digit in said multiplier, and means for changing the relation between said multiplicand and product potentials by one digital position once for each digital position of said multiplier.

2. 'I'he combination of means for producing potentials representative of a multiplicand, a totalizer for establishing potentials representative of a product, means for establishing potentials representative of a multiplier, means including a capacitor and a resistor responsive to said multiplicand and multiplier potentials for transferring said multiplicand to said totalizer once for each occurrence of a predetermined digit in said multiplier, and means for shifting said multiplicand potentials by one digital position once for each digital position of said multiplier.

3. The combination of means for .producing potentials representative of a multiplicand, a totalizer for establishing potentials representative of a product, means for establishing potentials representative of a multiplier, means including a capacitor and a resistor responsive to said multiplicand and multiplier potentials for transferring said multiplicand to said totalizer once. for each occurrence of a predetermined digit in said mul-tiplier. and means for shifting said product potentials by one digital position once ,for each digital position o! said multiplier.

4. The combination of means for producing potentials representative of a multiplicand, a totalizer for establishing potentials representative of a product, means for establishing potentials representative of a multiplier, means including an yamplifier biased to cutoff and beyond cutoi! in response to potentials'represent'ing a digit 1 and a digit 0 of said multiplicand for transferring said multiplicand -to said totalizer once for each occurrence of one of said digits in said multiplier, and means for changing the relation between said multiplicand and product potentials by one dig'ltal position once for each digital position of said multiplier.

5. The combination of means for producing potentials representative of a multiplicand, a totalizer for establishing potentials representative of a product, means for establishing potentials representative of a multiplier, and means including an electronic switch for transferring said multiplicand .to said totalizer once for each occurrence of a predetermined digit in said multiplier and for changing the relation between said multiplicand and product potentials by one digital position once for each digitalpositlon of said multiplier.

6. 'Ihe combination of a plurality of successive units each including a pair of electron discharge devices having anode and control electrodes and each operable to produce potentials representative of either of -two digits, means for polarizing said units to provide successive potentials representative of the successive digits of a number, and means connected between the anode electrode of one of said units and the corresponding control electrode of a succeeding one of said units for, shifting said digital representative potentials by one digital position.

'1. Ihe combination of a plurality of successive units each including a pair of electron discharge devices having anode and control electrodes and each operable to produce potentials representative of either of rtwo digits, means for polarizing said units to provide successive potentials representative of the successive digits of successive numbers, carry over means connected between said units for totalizing said numbers, and means connected between the anode electrode of one of said umts and the control electrode of a corresponding device of a succeeding one of said units for shifting said digital representative potentials by one digital position.

8. The combination of means for producing potentials in sets each representative of a different number, amplifying means biased to cut-oil in response to the occurrence of one digit in the iirst of said numbers and beyond cut-off in response to the occurrence of another digit in said first number, means for applying to said amplifying means one after the other the potentials of that set which is representative of the second of said numbers, and means for shifting .by one digital .position that set of potentials which is representative of said first number.

9, The combination of means for producing po- 1li` tentials in sets each representative of a diiierent number. amplifying means biased to cut-oil! in response to the occurrence of one digit in the first of said numbers and beyond cut-on in response .to the occurrence of another digit in said iirst number. means for applying to said amplifying means one after the other the potentials o1' that set which is representative of the second 'of said numbers, and means for changing by one digital position the relation between that set of potentials which is representative of said first number and .that set of potentials which is representative of the third of said numbers.

10. The combination of a plurality of trigger circuits each including a pair of electron discharge devices having a cathode and anode and an electrode for controlling the currentbetween said cathode and anode, means for establishing in successive ones of said circuits potentials representative ci the `successive digits of a num-ber.

and means coupling the anode of the electron discharge device of one trigger circuit to the control electrode of the corresponding electron discharge device of a succeeding one of said trigger circuits for shifting said digital representative potentials g5 by one digital position.

11. 'I'he combination of a plurality ot trigger circuits each including a. pair of electron discharge devices having a cathode and anode and an electrode for controlling the current between said cathode and anode. means for establishing in successive ones oi' said circuits .potentials representative of thesuccessive digits of a number. and means including a capacitor coupling the anode of the electron discharge device ot one trigger circuit to the'control electrode ot the corresponding electron discharge device of a succeeding lone of said trigger circui-ts for shifting said digital representative potentials by one digital position.

12. The combination of a plurality of successive units each including a pair of elements having anode and control electrodes and .each operable to produce either of two potentials. means for polarizing said units to provide potentials representative of different digits in a series o! numbers. and means connected between the `anode electrode ct one of said units and the corresponding control electrode of a succeeding one of said units for shifting said potentials by one digital Position.

LESLIE EJ I'LDRY.

REFERENCES CITED UNITED- STATES PATENTS Number Name Date A v1,080,245 Baldwin Dec.'- 2; 1913 2,123,459 Andersen July 12. i938 30' 2,192,612 Lang Mar. li,v 1940 2,409,689v Morton et al Oct. 22, 1946 

